Interaction with the watch is expected to be 5 seconds. Any longer, you should steer the user towards the iPhone (e.g. via hand-off).

Notifications on the watch are much more noticeable, so should be kept to a minimum

The force-touch provides a context-sensitive menu whichever screen the user is on. Although it’s less discoverable, it avoids the need for multiple swipes to reach an action screen.

The watch has a bezel! But it’s only visible if your app doesn’t have a black background. Interestingly, one of their recommend Apps, Toby (a cute dog) has a blue background that breaks Apple’s own guidelines.

Their are guidelines for the haptic/auditory feedback for events such as Notification, Up, Down, Success, Failure, Retry, Start, Stop, Click. For consistency, Apple need *every* developer to use the right effect with the right event – otherwise, users won’t intuitively know the meaning across different App contexts.

The click event is interesting – it gives granularity to adjustments, but could easily be over-played – so it’s recommend to exercise restraint.

There are templates for glances – and they should “deep link” to the main App for more information. Again, consistency of layout between the glances for different Apps is important to the continuity of experience for users.

Sessions are available for longer interaction with a watch app, intended for fitness apps (e.g. a period in the gym). Yet again, it’s easy to see App developers over-using this feature to avoid the watch returning to the time screen.

Much relies on Apple policing these guidelines, which could be a lot of work.